The unauthorized copying of media content, often referred to as piracy, is a major concern to the authors, publishers, and distributors of such content. For example, audio content such as songs and video content such as movies can often times be easily copied by people without the legal right to do so. This problem has become particularly troublesome as digital content becomes more pervasive, as storage devices become increasingly cheaper, and as computers become more interconnected (e.g., via the Internet). Unauthorized copying of media content can take place in several forms. For example, digital content may be copied byte by byte on a computer. By way of another example, digital content may be played back in analog form and an analog recording made of the content, which in turn can be converted to digital form again, such as a song stored in digital form being played back in analog form recorded on an analog tape recorder and then the analog recording converted back to digital form.
Various solutions have been proposed to prevent piracy of digital content. One such solution is to encrypt the digital content. Such encryption can often prevent, or at the very least make difficult, the use of unauthorized copies of the digital content. However, the content is inevitably decrypted at some point prior to the final presentation to the user and can be copied while it is unencrypted. For example, in the extreme case, encryption typically does not prevent an individual from making an analog recording of the digital content after it has been decrypted and converted to analog form, and then storing the analog recording in a digital form. Such a digital to analog to digital copying scheme typically results in a newly saved digital recording that is not encrypted, and thus can be freely copied and distributed to unauthorized users.
Another proposed solution is to add watermarks or fingerprints to the digital content that cannot be removed without causing noticeable damage to the content. Software programs can then be designed to not copy any content that is watermarked or fingerprinted. Such proposed watermarks or fingerprints are designed such that they cannot be removed even when making an analog copy of the digital content. However, concerns have been raised as to whether such watermarks or fingerprints can be created and used in an effective manner.
The invention described below addresses these disadvantages, providing methods and systems for detecting pirated content.